Dynamic force microscopy imaging of native membranes

We employed magnetic ACmode atomic force microscopy (MACmode AFM) as a novel dynamic force microscopy method to image surfaces of biological membranes in their native environments. The lateral resolution achieved under optimized imaging conditions was in the nanometer range, even when the sample was only weakly attached to the support. Purple membranes (PM) from Halobacterium salinarum were used as a test standard for topographical imaging. The hexagonal arrangement of the bacteriorhodopsin trimers on the cytoplasmic side of PM was resolved with 1.5nm lateral accuracy, a resolution similar to images obtained in contact and tapping-mode AFM. Human rhinovirus 2 (HRV2) particles were attached to mica surfaces via nonspecific interactions. The capsid structure and 2nm sized protein loops of HRV2 were routinely obtained without any displacement of the virus. Globular and filamentous structures on living and fixed endothelial cells were observed with a resolution of 5-20nm. These examples show that MACmode AFM is a favorable method in studying the topography of soft and weakly attached biological samples with high resolution under physiological conditions.     

Erweiterung des Stadions Innsbruck “Tivoli Neu” für die Fußballeuropameisterschaft 2008

Stadium Innsbruck “Tivoli Neu” extended for the European Football Championship 2008. Austria and Switzerland are the hosts of the European Football Championship EURO 2008. Each of both countries needs four stadiums with at least 30000 spectator seats. Innsbruck had a facility with a capacity of nearly 15000 seats. This existing stadium “Tivoli Neu” has therefore to be extended. The community of Innsbruck requests, that after the Championship the stadium has to be reconstructed into the original state.     

Special Economic Zones in South Africa: Reflections from International Debates

South Africa’s experience with spatial economic interventions has had a chequered history with the Industrial Development Zone programme most recently failing to generate anticipated development. Current policy has shifted to the imminent launch of Special Economic Zones (SEZs) as tools for national (re)industrial development and supporting underdeveloped regions. This paper reflects on recent South African experience with spatial economic interventions and international experience with SEZs paying particular attention to their strengths, weakness and key establishment considerations. It is argued that unfolding South African SEZ planning can be strengthened by learning from the ‘good’ and ‘bad practice’ of international SEZs.     

Passive Grubenwasserreinigung als Alternative zu aktiven Systemen

Um kontaminiertes Grubenwasser langfristig kostengünstig reinigen zu k?nnen, sind Methoden mit geringstm?glichen Investitions- und Unterhaltungskosten n?tig. Dazu wurden in Gro?britannien und Deutschland in den zurückliegenden Jahren unterschiedliche passive Reinigungssysteme in Betrieb genommen (z. B. anoxische Karbonatkan?le, konstruierte Feuchtgebiete, reaktive Barrieren, Gro?oberfl?chenfilter).     

Effects of pH on the bioconcentration of pyrene in the larval midge, Chironomus riparius

Bioconcentration, depuration and biotransformation of the polycyclic aromatic hydrocarbon, pyrene, were studied at pH 4, 6 and 8 with larval stages of the chironomid midge, Chironomus riparius. ¹⁴C-labelled pyrene was applied. The results revealed pH-dependant bioconcentration and depuration-kinetics as well as biotransformation of pyrene. At higher pH the bioconcentration rate (k₁) was greater than at lower pH. Hereby the bioconcentration rate correlated with the accumulation potential of pyrene. That means at pH 8 the larvae accumulated pyrene strongest, at pH 4 the bioconcentration of the larvae was lowest. Due to biotransformation of pyrene the calculated bioconcentration factor (BCF) based on total ¹⁴C found in the larvae. Depuration revealed a biphasic kinetic. Data were fit with a two compartment model to calculate the volume of each of the two compartments. To calculate for the depuration rate (k₂), data were additionally fit with a one compartment model. The larvae displayed an intriguing pH-dependent behaviour: At pH 4 the Chironomus larvae started to increase mucus-production of the salivary glands and accelerated the built up of their tubes. The latter were of “cocoon”-like structure. At pH 8 the composition of the tubes was more loose. It is hypothezised that this response to an acidified environment caused the reduced bioconcentration rate as well as the reduced biconcentration.     

Informal Sector Business Tourism in the Global South: Evidence from Maseru, Lesotho

Domestic tourism is a neglected theme within tourism scholarship about the global South. This article addresses informal sector domestic tourism and is anchored upon the typology of tourism by Gladstone (2005) in which distinctions are drawn between international and domestic tourism and formal and informal sector tourism. The specific focus is informal sector business tourism, the nature of which challenges Western definitions of business tourism. The study reports findings from 52 interviews conducted with informal business tourists and accommodation providers in Maseru, Lesotho’s capital city. It is revealed the nature of low-income informal sector business tourism in the global South is radically different to that of conventional business tourism in terms of its organisation, characteristics of business tourists, and impacts. Arguably, informal sector business tourism is inherently pro-poor in its local impacts. Further comparative research work is required concerning these forms of ‘invisible’ tourists in African cities.     

Parallel kinematic concept for stationary high performance cutting in wood machining centers

In recent years parallel kinematic machines for wood machining have come into use more frequently. Despite first promising prototypes, these machines are single solutions for specific applications. To meet the requirements of shorter product life cycles and higher product diversity, high flexibility is demanded of the machining system. This paper presents a new wood machining center obtaining both, the reduction of the primary and secondary processing times. The machine concept, based on a parallel kinematic structure, allows high operating speeds and accelerations not only for workpiece machining but also for handling. Thus, the machine can be used without any external handling devices. The kinematic structure originates from a plane closed five-bar chain with two linear drives and additional drive axes for stroke and rotation. In order to increase the useable workspace a continuous motion between different assembly modes is realized. To guarantee a high feed rate and to minimize set-up times, an optimized dust exhaustion is included.     

Damping models for machine tool components of linear axes

To simulate the dynamic behaviour of machine tools, the stiffness, damping and inertia parameters of the structure are needed. While masses and stiffness parameters of structural parts can be obtained with a static measurement, the determination of damping parameters requires a thorough methodology. In this paper the common methodology for the identification of local damping parameters of machine components was extended by an additional step to isolate the damping of the test object more precisely. Furthermore test benches as well as the identified damping models for components of an exemplary linear axis are presented.